An implementation of Simon Peyton-Jones's Santa-themed concurrency simulation from his article "Beautiful Concurrency" which originally appeared in the book Beautiful Code in 2007.
This recreation of the simulation is built using Rust and Convex. Convex is a backend application platform that allows you to easily build sophisticated, distributed, reactive apps.
A copy of SPJ's original paper is here:
https://www.microsoft.com/en-us/research/wp-content/uploads/2016/02/beautiful.pdf
Santa repeatedly sleeps until wakened by either all of his nine reindeer, back from their holidays, or by a group of three of his ten elves. If awakened by the reindeer, he harnesses each of them to his sleigh, delivers toys with them and finally unharnesses them (allowing them to go off on holiday). If awakened by a group of elves, he shows each of the group into his study, consults with them on toy R&D and finally shows them each out (allowing them to go back to work). Santa should give priority to the reindeer in the case that there is both a group of elves and a group of reindeer waiting.
This implementation aims to replicate the standard output of the original Haskell version.
Ho! Ho! Ho! let’s deliver toys
Reindeer 8 delivering toys
Reindeer 7 delivering toys
Reindeer 6 delivering toys
Reindeer 5 delivering toys
Reindeer 4 delivering toys
Reindeer 3 delivering toys
Reindeer 2 delivering toys
Reindeer 1 delivering toys
Reindeer 9 delivering toys
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Ho! Ho! Ho! let’s meet in my study
Elf 3 meeting in the study
Elf 2 meeting in the study
Elf 1 meeting in the study
$ npm i
$ npx convex init
$ npx convex deploy
It looks something like https://furry-bunny-111.convex.cloud. You'll need this
to pass to the rust app. The next step will assume this URL is in the
DEPLOYMENT_URL environment variable.
$ cargo run -- $DEPLOYMENT_URL